From: Chris Thompson [mailto:cet1@cus.cam.ac.uk]
Ethan Torretta ejt@tellme.com writes:
"Michael J. Tuciarone" tooch@netapp.com wrote:
As filers have received more main memory, we began running out of reserved disk areas before the whole core was dumped. The actual ratio of memory to disk depends on memory size and disk model; the larger the ratio the more likely you'll be unable to dump the whole core. In response, we implemented the compressed
core feature.
Now if the filer computes there isn't enough disk space
to save the
entire core uncompressed, we compress the core before
writing it out.
This makes me very interested in providing enough disks to allow uncompressed cores. However, looking at the documentation
I don't think
that's going to happen. According to the SAG, each disks
provides only
20 MB of dump space, so for an F760 with 1024 MB of main
memory, fifty-two
disks will be necessary for an uncompressed dump. Is this
correct?
The chart still says only fourteen for "256 or more." I've
got fourteen
on each filer; if twenty, say, would do it, I'd rearrange
filers so that
the most sensitive ones had twenty, but fifty-two is out of
the question.
The problem would seem to be that the 20 MB reserved area hasn't altered from the days of 2 GB, maybe 1 GB, discs, and so things have got out of proportion.
How about using the space wasted by "right-sizing" for dumps? Only if it exists, of course, but in practice it will, and will be a lot more than 20 MB per disc!
As you said above, the 20MB reserved area is the same on all sized disks. However we do use the space that is left over after right-sizing. The size of the space varies with the capacity of the disk.
In a coming release compression of the core will be deferred if there is enough space available on the disk. In addition the core will be sprayed to multiple disks in parallel (it currently is written synchronously to one disk at a time). This is for fibre channel disks only. -steve
From "Watanabe, Steve" on Thu, 23 Mar 2000 06:05:13 PST:
In a coming release compression of the core will be deferred if there is enough space available on the disk. In addition
Cool. So in 5.3.5, does it check to see if an uncompressed dump is possible, or does it compress regardless of available space?
the core will be sprayed to multiple disks in parallel (it currently is written synchronously to one disk at a time).
Sweet! That's what we like to hear! =)
-- Jeff
-
Jeff Krueger -
Watanabe, Steve